Discrete groundwater level datasets are interpolated often using kriging group of models to produce a spatially continuous groundwater level map. There is always some level of uncertainty associated with different interpolation methods. Therefore, we developed a new trend function with the mean groundwater level as a drift variable in the regression kriging approach to predict the groundwater levels at the unvisited locations. Groundwater level data for 29 observation wells in Adyar River Basin were used to assess the performance of the developed regression kriging models. The cross-validation results show that the proposed regression kriging method in the spatial domain outperforms other physical and kriging-based methods with R2 values of 0.96 and 0.98 during pre-monsoon and post-monsoon seasons, respectively.

The objective of this research is to develop a fuzzy-based groundwater sustainability index (FGSI) model to evaluate the sustainability of groundwater system at selected cities in Asian.   The new Mamdani type fuzzy-based inference system known as FGSI was developed. It contains five components and twenty-four indicators, which covers five dimensions of sustainability, namely, environmental, social, economic, mutual trust, and institutional. The FGSI model offers a novel combination of indicators, which covers aspects of groundwater quality, quantity, and management. An attempt was made to develop a robust index for estimating the groundwater sustainability. The model was evaluated for selected cities in Asian with different defuzzification methods and compared with the conventional method. The centroid defuzzification method produced well diversified results compared with other methods, including conventional method. The overall groundwater sustainability of Hyderabad of India was estimated as highly sustainable and, Lahore of Pakistan, Bangkok of Thailand, Ho Chi Minh City of Vietnam, and Yangon City of Myanmar were estimated as moderately sustainable. The FGSI model may help to policy and decision makers to provide a reliable and resilient sustainable management system in the cities by identifying the indicators for the improvement.

Ho Chi Minh City (HCMC), Vietnam has undergone tremendous transformation in land-use practices in the past few decades. The groundwater-related issues have also been a major concern in the fast-growing southern city of Vietnam. Quantitative prediction of the impact on groundwater recharge due to changes in the land-use pattern of a watershed is crucial in developing sound groundwater management schemes. This study aims to evaluate the impacts of change in land-use patterns on the quantity of groundwater recharge in HCMC. An empirical land-use projection model (Conversion of Land-use and its Effects, Dyna-CLUE) and a hydrological model (Soil and Water Assessment Tool, SWAT) was used for the study. Three future land-use scenarios of Low Urbanization Scenario (LU), Medium Urbanization Scenario (MU) and High Urbanization Scenario (HU) were developed in Dyna-CLUE focusing on the increase of built-up area to generate land use maps of HCMC until the year 2100. The land-use maps for all three scenarios were then used in the calibrated hydrological model SWAT to get the future recharge in the near future (2016–2045), mid future (2046–2075) and far future (2076–2100). The recharge was observed to increase in the far future of LU by 10% while reduction of 30% and 52%